Abstract
BackgroundIntracranial aneurysms more often occur in the same arterial territory within families. Several aneurysm locations are associated with specific circle of Willis variations. We investigated whether the same circle of Willis variations are more likely to occur in first-degree relatives than in unrelated individuals.MethodsWe assessed four circle of Willis variations (classical, A1-asymmetry, incomplete posterior communicating artery and fetal circulation) in two independent groups of families with familial aneurysms and ≥2 first-degree relatives with circle of Willis imaging on MRA/CTA. In each (index) family we determined the proportion of first-degree relatives with the same circle of Willis variation as the proband and compared it to the proportion of first-degree relatives of a randomly selected unrelated (comparison) family who had the same circle of Willis variation as the index family’s proband. Concordance in index families and comparison families was compared with a conditional logistic events/trials model. The analysis was simulated 1001 times; we report the median concordances, odds ratios (ORs), and 95% confidence intervals (95%CI). The groups were analysed separately and together by meta-analysis.ResultsWe found a higher overall concordance in circle of Willis configuration in index families than in comparison families (meta-analysis, 244 families: OR 2.2, 95%CI 1.6–3.0) mostly attributable to a higher concordance in incomplete posterior communicating artery (meta-analysis: OR 2.8, 95%CI 1.8–4.3). No association was found for the other three circle of Willis variations.ConclusionsIn two independent groups of families with familial aneurysms, the incomplete PcomA variation occurred more often within than between families suggesting heritability of this circle of Willis variation. Further studies should investigate genetic variants associated with circle of Willis formation.
Highlights
Intracranial aneurysms are weak pouches in the walls of brain arteries that occur in 3.2% of the population [1]
We assessed four circle of Willis variations in two independent groups of families with familial aneurysms and !2 first-degree relatives with circle of Willis imaging on magnetic resonance angiography (MRA)/ computed tomography angiography (CTA)
We found a higher overall concordance in circle of Willis configuration in index families than in comparison families mostly attributable to a higher concordance in incomplete posterior communicating artery
Summary
Intracranial aneurysms are weak pouches in the walls of brain arteries that occur in 3.2% of the population [1]. Intracranial aneurysms are located at the circle of Willis, a circulatory anastomosis of arteries located at the base of the brain. Variation in the configuration of the circle of Willis is common. Aneurysms are more likely to occur in the same arterial territory in the circle of Willis within affected members of the same family than in affected individuals from unrelated families [6]. Aneurysm location may be influenced by variation in the configuration of the circle of Willis. Several aneurysm locations are associated with specific circle of Willis variations. We investigated whether the same circle of Willis variations are more likely to occur in first-degree relatives than in unrelated individuals
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